In the case of custody, a judge could say each parent getting a child for 50% of the hours in a week is equal custody. One parent gets all of the sleeping hours. That is not equitable.
or one parent gets all of the vacation weeks, while the other gets primarily school weeks. Equal, but not equitable.
I've seen examples of both of the above - many of the second example.
I see more examples of equitable custodial arrangements now than I did 20/30/40 years ago - in our jurisdiction, partly due to one of cavfancier's aunts, an important activist judge. I also see more custodial arrangements that factor the children's opinions into the assessment of equity. This was once a serious gap IMO.
As a result, we see fewer cases of 'glamour' parents now, which I think is good for children and families.